Authorities have warned that Murray River floods may not recede until 2023. 

For months, towns in north-west Victoria have been preparing for flooding and evacuations, as Murray River floodwaters continue to rise slowly over the course of several weeks.

The Murray is around 2,500 kilometres long with a gradient of about 9 cm per 1.6 km, meaning water flowing down it takes a long time to go anywhere.

This has given emergency authorities vital planning time, however, the slow creep of water means people who choose to stay in their homes could be trapped by floodwater into 2023.

State Emergency Service incident controller for Mildura Mark Cattell says some predictions are impossible to make until the water arrives. 

“The issue we have is we don't know when the water will stop going into [the Murray],” he said.

“There's still water coming in from the Edwards River, so we won't know until all the water arrives.”

Evacuation orders have been issued for several Murray River towns during the upcoming flooding event. 

“If they decide not to evacuate and their house is going to be inundated, they need to be prepared to be there for the long haul,” Mr Cattell said.

“If the water does get up it could push septic back into your toilet or into your house … for three or two months. It's something they really need to consider.

“They need to make sure they have enough medication, water, an ability to keep food and water fresh, they also might need generators but we don't want people running those in houses.”